A bipartisan group of lawmakers will introduce legislation Thursday to prevent the U.S. Department of Agriculture from continuing deadly experiments on kittens.

"The USDA's decision to slaughter kittens after they are used in research is an archaic practice and horrific treatment, and we need to end it," Sen. Jeff Merkley, D-Oregon, the Senate bill's lead sponsor, said in a statement to NBC News.

The agency has been breeding kittens in Beltsville, Maryland, and infecting them with a parasite that can cause toxoplasmosis, a food-borne illness. Scientists harvest the parasites from their stool for two to three weeks, and then euthanize and incinerate the cats.

The agency has said animal rights advocates' claim they've been experimenting on 100 cats annually is overblown, but a USDA administrator told Congress last year that "2,988 cats have been used in these research efforts that began in 1982."

Sen. Jeff Merkley, D-Ore. speaks to reporters just outside the Senate chamber on Capitol Hill on April 5, 2017 in Washington.J. Scott Applewhite

The bills are being championed by the watchdog group White Coat Waste Project, which has run an ad campaign against the experiments in Maryland. The group's vice-president of advocacy and public policy, Justin Goodman, said its members "want this horrific program relegated to the litter box of history."

"Three thousand healthy kittens killed and $22 million wasted on decades of cruel and unproductive government experiments should alarm budget hawks and advocates alike," Goodman said.

The USDA's Agricultural Research Services has defended the experiments as "life-saving research." The agency maintains the animals have to be euthanized to stop the parasite from infecting people, but the American Veterinary Medical Association has said that handling cats who've had it is "unlikely to pose a risk" for humans. The USDA said last year it was looking for alternatives to the cat testing.

The Centers for Disease Control and Prevention says toxoplasmosis is one of the leading causes of death from foodborne illnesses in the country. Over 40 million Americans carry the parasite without a problem, but it can have "severe consequences" for people who are pregnant or have a compromised immune system.

Lawmakers are calling the bill the Kittens in Traumatic Testing Ends Now — or KITTEN — Act.

"The KITTEN Act will protect these innocent animals from being needlessly euthanized in government testing, and make sure that they can be adopted by loving families instead," said Merkley, who earlier this week announced he would not be running for president."

"The fact that we need a piece of legislation to tell the federal government to stop killing kittens is ridiculous on its face," said Rep. Brian Mast, R-Fla., who introduced the measure in the House, "but what's even worse is when you hear the details that the government is actually breeding hundreds of these cats just to intentionally feed them parasite-ridden raw meat and then kill them even though they're perfectly healthy."

Similar legislation was introduced earlier this year to prevent the Department of Veteran Affairs from continuing often-gruesome testing on dogs, which included forced heart attack experiments. That legislation is called the Preventing Unkind and Painful Procedures and Experiments on Respected Species Act, or PUPPERS.